Referring to Problem 11-28, flows are projected to increase to 18 mgd; advanced primary...

Referring to Problem 11-28, flows are projected to increase to 18 mgd; advanced primary treatment is being considered until a new aeration basin is built. What chemicals should be added to increase suspended solids removal. Settling tests showed that BOD is removed in the same proportion as suspended solids. What is the resulting loading to the aeration basins? Will the sludge settle properly?

Problem 11-28:

A conventional aeration plant has a flow of 12 mgd with a BOD of 190 mg/l. The primary clarifier removes 25 percent of the BUD. The 10 aeration basins are 40 ft wide, 100 ft long, and 15 ft deep. Determine the liquid detention time, loading rate, F/M ratio (with an MLSS of 2350 mg/l), sludge age (with 5330 lb/day waste sludge Eff. SS = 20mg/l. Refer to Figure 11-26 and determine if sludge will settle properly.